Method of weld repairing of a section of a metallic cylindrical member

Abstract

A method of repairing a section of a metallic cylindrical member, such as a turbine shaft, having surface defects and a keyway thereon, by machining the surface to a depth less than the depth of the keyway and inserting a half key in the keyway, and machining the combination to provide a continuous surface for welding. A weld material is then deposited over the continuous surface formed to a thickness which provides a diameter greater than the initial diameter of the shaft. The weld material is machined to give a member having the initial diameter and the key member is removed to provide a repaired member having a keyway therein.

What is claimed is: 
     
       1. A method of weld repairing a section of a metallic cylindrical member having an initial diameter to remove defects in the surface thereof, which section has a keyway in the surface area thereof comprising: mechanically removing the surface of said section of said cylindrical member, to a depth less than the depth of said keyway, to remove the surface defects and provide a welding surface;   inserting a key member, of a material that is weld compatible with the metallic material of the section of the cylindrical member, in said keyway to provide a key member surface flush with said welding surface;   recording the location of said keyway in said cylindrical member;   depositing a weld metal over said welding surface and said key member surface to provide weld metal thereon, such that the section of the cylindrical member with said weld metal is larger in diameter than said initial diameter;   machining said weld metal to provide a layer of weld metal on the section of the cylindrical member of a diameter equal to said initial diameter; and   removing the key member from said keyway to provide a repaired section of the cylindrical member of said initial diameter having said keyway in the surface area thereof.   
     
     
       2. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein the outer surface of said cylindrical member has defects thereon and the keyway in the surface area adjacent said outer surface. 
     
     
       3. The method of weld repairing a section of a metallic cylindrical member as defined in claim I, wherein said cylindrical member has a bore therethrough and an inner surface facing said bore, with the defects being in said inner surface and the keyway in the surface area adjacent said inner surface. 
     
     
       4. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein said key member, when inserted into said keyway, initially has an exposed end surface extending from the keyway, and said exposed surface is mechanically removed to provide said key member surface flush with said welding surface. 
     
     
       5. The method of weld repairing a section of a metallic cylindrical member as defined in claim 4, wherein the mechanical removing of said surface of said section and of said portion of said key member is by machining. 
     
     
       6. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein said metallic cylindrical member is an extension shaft of a steam turbine. 
     
     
       7. The method of weld repairing a section of a metallic cylindrical member as defined in claim 6, wherein said extension shaft is composed of a metal selected from the group consisting of an AISI 1040 steel and a CR-MO-V ferrous alloy. 
     
     
       8. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein said metallic cylindrical member is a high pressure steam turbine rotor. 
     
     
       9. The method of weld repairing a section of a metallic cylindrical member as defined in claim 8, wherein said high pressure steam turbine is composed of a Cr-Mo-V ferrous alloy. 
     
     
       10. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein said metallic cylindrical member is a low pressure steam turbine rotor. 
     
     
       11. The method of weld repairing a section of a metallic cylindrical member as defined in claim 10, wherein said low pressure steam turbine rotor is composed of a Ni-Cr-Mo-V ferrous alloy. 
     
     
       12. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein said depositing of weld metal over said welding surface and said key member is carried out by a gas tungsten arc welding, plasma-arc welding, electron beam welding, laser beam welding, or gas metal arc welding process. 
     
     
       13. The method of weld repairing a section of a metallic cylindrical member as defined in claim 1, wherein said key member is of a metallic composition identical to the metallic composition of said metallic cylindrical member. 
     
     
       14. A method of weld repairing a section of a metallic cylindrical shaft having an initial diameter to remove defects in the outer surface thereof, which section has a keyway in the surface area thereof comprising: mechanically removing the surface of said section of said cylindrical shaft, to a depth less than the depth of said keyway, to remove the surface defects and provide a welding surface;   inserting a key member, of a material that is weld compatible with the metallic material of the section of the cylindrical shaft, in said keyway, which key member has an exposed end surface extending from the keyway;   mechanically removing said exposed surface to provide a key member surface flush with said welding surface;   recording the location of said keyway in said cylindrical shaft;   depositing a weld metal over said welding surface and said key member surface to provide weld metal thereon, such that the section of the cylindrical shaft with said weld metal is larger in diameter than said initial diameter;   machining said weld metal to provide a layer of weld metal on the section of the cylindrical shaft of a diameter equal to said initial diameter; and   removing the key member from said keyway to provide a repaired section of the cylindrical shaft of said initial diameter having said keyway in the surface area thereof.   
     
     
       15. A method of weld repairing a section of a metallic cylindrical sleeve having an initial diameter to remove defects in the surface thereof, which section has a bore therethrough and an inner surface facing said bore, with the defects in said inner surface, and a keyway in the surface area adjacent said inner surface comprising: mechanically removing the surface of said section of said cylindrical shaft, to a depth less than the depth of said keyway, to remove the surface defects and provide a welding surface;   inserting a key member, of a material that is weld compatible with the metallic material of the section of the cylindrical sleeve, in said keyway, which key member has an exposed end surface extending from the keyway;   mechanically removing said exposed surface to provide a key member surface flush with said welding surface;   recording the location of said keyway in said cylindrical sleeve;   depositing a weld metal over said welding surface and said key member surface to provide weld metal thereon, such that the section of the cylindrical sleeve with said weld metal is larger in diameter than said initial diameter;   machining said weld metal to provide a layer of weld metal on the section of the cylindrical sleeve of a diameter equal to said initial diameter; and   removing the key member from said keyway to provide a repaired section of the cylindrical sleeve of said initial diameter having said keyway in the surface area thereof.